Numerical Investigation of Turbulent Heat Transfer Properties at Low Prandtl Number

Sodium-cooled fast reactor (SFR) which is one of the most promising candidates to meet the Generation IV International Forum (GIF) declare has drawn a lot of attentions. Turbulent heat transfer in the liquid sodium which is one of those low Prandtl fluids is an extremely complex phenomenon. The limitations of the commonly used eddy diffusivity approach have become more evident for low-Prandtl fluids. The current study focuses on the assessment and optimization of the existing modeling closure for single-phase turbulence in liquid sodium based on the reference results provided by LES method. In this paper, a wall-resolved Large-Eddy Simulation was performed to simulate the flow and heat transfer properties in a turbulent channel at low Prandtl number. The simulation results are firstly compared with the DNS results obtained from literature. A good agreement demonstrated the capability of the employed numerical approach to predict the turbulent and heat transfer properties in a low Prandtl number fluid. Consequently, new reference results were obtained for typical Prandtl number and wall heat flux of SFR. A time-averaged process has been employed to evaluate temperature profile quantitatively as well as turbulent heat flux. Their dependency was also evaluated based on a systematic CFD simulation which covers the typical Reynolds numbers of SFR. Based on the obtained reference results, the coefficients employed in the algebraic turbulent heat flux model (AFM) are calibrated. The optimized coefficients provide a better prediction accuracy of heat transfer properties for typical flow conditions of SFR if comparing with the existing models found in the literature.